Some communications techniques use “linear modulation using non-linear components” (LINC) modulation. LINC modulation is sometimes referred to as constant envelope out-phasing. LINC modulation transforms traditional Cartesian modulated RF signals with I and Q components to a combination of two constant envelope signals. The constant envelope signals are referred to as S1 and S2 signals. The S1 and S2 signals are phase modulated and can have any value in the phase domain.
Two issues make LINC modulation difficult at higher frequencies. The first is the calculations required to achieve LINC modulations. More specifically, inverse cosine and inverse tangent functions must be calculated. These functions are time consuming to calculate. In some embodiments, look up tables are used to determine the inverse cosine and inverse tangent values, but the look up tables require extensive memory, which is costly. The second problem is that the S1 and S2 signals are phase modulated, which is difficult to achieve with the accuracy required at higher frequencies.